The present invention relates generally to material monitors for a dispensing system and more specifically to a nonelectrical monitor and alarm that totals material dispensed for use in hazardous environments.
The use of mechanical indicators such as gauges and another annunciators is well known. With the advent of relatively inexpensive integrated circuits, electrical gauges and alarms have replaced the mechanical gauges and indicators. In certain environments, the possibility of any sort of electrical spark is very hazardous. An example of one such environment is in the plastic and coating spraying industry where resin and catalysts are mixed together and sprayed onto a surface. There are many variables which must be monitored in the spraying environment. The spraying environment generally includes a series of mechanical gauges, operating on pressure, to indicate the pressures throughout the system as well as flow rates. The use of microprocessors and other forms of electrical equipment generate and interpret electric signals to determine the flow and mass rate as well as the total amount of material being dispensed. Optical sensors and other devices are used. Not only are these electrical systems somewhat expensive, but again they cannot be used in hazardous environments where any sort of electrical spark is considered dangerous. Also, electrical systems must meet strict Underwriters and local codes and regulations.
In the prior art material dispensing monitoring, the specific gravity of the material being dispensed had to be known to convert volume to weight of amount of material dispensed. With less sophisticated systems, merely a count of the number of the cycles of the pump was provided and this count value had to be converted using a table knowing the capacity of the pump and the specific gravity of the material being dispensed. In the more sophisticated electronic systems, the specific gravity would also have to be known and provided to the electronics which would then convert it to an appropriate weight of material.
Where the material being dispensed are a mixture of two materials, the specific gravity will vary if the ratio of the components should vary during the dispensing cycles. Similarly, the seals on the pump may become worn and therefore the amount of material dispensed for each cycle of the pump will not be that of the known capacity of the pump. Therefore, the count will not represent the appropriate volume and if a two material system, the ratio of the mixture will vary and thus the density of the mixture. Thus there is a need for a system which will also provide the ability to determine the specific gravity of the material being dispensed.
Thus it is an object of the present invention to provide a material dispensing monitor requiring no electrical parts.
Another object of the present invention is to provide a material dispensing monitor which provides a direct readout of the weight of material being dispensed.
A still even further object of the present invention is to provide a material dispensing monitor which is capable of being used to determine the specific gravity of the material being dispensed.
These and other objects are achieved by providing a pair of telescopic members, a first member having an encoder mounted thereon and a second member having a sensor mounted thereon. The telescopic members are adjustably mounted between a pump and a first securement for determining the displacement of the members relative to each other for a cycle of the pump as a function of the specific gravity of the material being dispensed.
The sensor provides a series of pulses which are generally counted and displayed. The sensor and the counter circuit are pneumatic to determine the weight of material being dispensed. The encoder includes a predetermined plurality of spaced openings corresponding to a predetermined volume per pump cycle such that the displayed count is a direct reading of weight. To connect the telescopic members to the pump, a lever is provided pivotally connected at a one end and driven at its other end by a pump to oscillate about the pivot. The first and second members are connected between the lever and the first securement. The lever and the first securement both include a plurality of openings to which the first and second members are adjustably mounted. Indicia are provided on the plurality of openings to indicate the specific gravity. The lever and the first securement may also include openings for a slave pump.
The monitoring system can also include an alarm system wherein a predetermined weight is selected and the sensed accumulating weight for a particular job is compared against the predetermined weight to provide an alarm or annunciation when the predetermined weight has been reached. This will provide notice to the operator that he has dispensed a predetermined weight of material. A totalizer may also be provided to indicate the total amount of material being dispensed within the course of a predescribed period, for example a day. The alarm or monitoring system includes all pneumatic elements and logic.
A method of determining specific gravity using the encoder and sensor system previously described, includes dispensing a predetermined volume into a container, weighing the predetermined volume, and comparing the weight with the displayed weight using the above encoder and monitoring system. If the measured weight and displayed weight don't agree, adjust the connection of the encoder and sensor to different specific gravity and repeat the filling, weighing, and comparing steps until the weight measured matches the displayed weight. Then, the indicia of the specific gravity will be the specific gravity of the material dispensed. This allows determining the specific gravity of unknown material, or verifying the specific gravity and therefore the mixture of mixed materials being dispensed as well as determining the efficiency of the seals of the pump.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.